The Hurricane of Sept. 29th, 1915,
and
Subsequent Heavy Rainfalls.

Report
of
Geo. G. Earl, Gen'l Supt.
to
Sewerage and Water Board of New Orleans,
October 14th, 1915.a

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The Hurricane.

To the Honorable President and Members, Sewerage and Water Board of New Orleans:

Gentlemen — The hurricane of September 29th, with its great rainfall, high winds and high tides, put all of the systems operated by the Sewerage and Water Board to the most severe tests.

This storm began on the night of September 28th, with rain and a gradually increasing northeast wind. By 7 a. m. on the 29th the wind had increased to a gale of 40 miles an hour, and during the day both wind and rain increased in intensity until, between 5 and 5:30 p. m., when the Weather Bureau reports there was a sustained wind velocity of over 80 miles an hour,b and velocities up to 120 and 130 miles for the hardest gusts, with 8.2 inches of rainfall and a minimum barometer reading of 28.11 inches.

Drainage System Operating Morning of Storm

At 7 a. m. on the 29th the drainage system was operating normally, and as the rain increased the Central Power Station was able to operate all of the pumps necessary to take care of the water as it reached the various pumping stations.

The first indication of trouble was at 10:50 a. m., when heavy short-circuits occurred, and the pumps operating at Station Nos. 1, 3 and 7, and a few moments later at 6, went out of step. At that time the water on the suction side of the various pumping stations stood as follows:

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Portions of City below Mean Lake Level

In order to comprehend the significance of these and other figures given later, it should be remembered that elevation 20 C. D. is substantially the mean low lake level, and also the elevation of the land in the lower portions of the city. So that any elevation of 19 C. D. or lower, at the various pumping stations, indicates that the water in the low areas is within the canal banks and occasioning no serious inconvenience.

Operation of Drainage System Stopped by 6 o'clock p. m.

From 10:50 a. m. the drainage system was operated under increasing difficulty. Power was sent out into the transmission lines constantly until 5 o'clock p. m., and the pumps at the various stations were operated as best they could be, but were repeatedly put out of step by short-circuits caused by wires and trees falling across the transmission lines, which in turn caused interruption in the operation of the pumps.

The main line from Station 6 to Power House No. 2 was entirely put out of commission by a huge oak tree which fell across it, and the line to Station No. 1 was short-circuited by wires falling across it; so that Power House No. 2 was entirely out of commission.

At 4:35 o'clock p. m. the top 50 feet of the 175‑foot steel stack of the Heine boiler battery at the Central Power Station broke off and fell through the roof of the boiler room, tearing down roof trusses and small steam and water pipes, but fortunately missing the main steam line by a few inches and falling in the space reserved for future boiler installations, so that none of the boilers were damaged and only the Heine boilers were put out of commission.

By 6 o'clock P. M. the storm had reached such magnitude
p5that it was feared that the whole building would be destroyed, and as it had been found impossible to maintain current on any of the transmission lines after 5 o'clock, and the last generators had been shut down, the Chief Engineer ordered the men to the basement for safety, having first carefully examined all boilers and pipes and ascertained that, without further disaster, everything except the Heine boilers — that is, the eight Babcock & Wilcox boilers, could be operated.

Overflow of Lake Water

During the day frequent advices were received of small overflows of various of the levees. Three of these were in the locality of the various pumping stations and were taken care of by the Sewerage and Water Board contractors working in the neighborhood.

At 5 o'clock p. m. the water on the suction side of the stations stood as follows:

and the lake level appears to have been at elevation ranging from 25.0 C. D. to 26.2 C. D., and rapidly fluctuating.

Center, and Passing of Hurricane

At about 6 o'clock p. m. there was a slight lull in the wind, and shortly after a reversal of direction, with very high velocities for the greater portion of the night, but not nearly so high as during the afternoon.

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Drainage Operations Resumed Thursday and Friday

The linemen were kept on duty all night, and early Thursday morning were sent out to clear the lines. All work was at a very great disadvantage because of lack of communication through telephones, and the Board's Ford cars were put into service in all directions, and all available forces directed to stand by and co‑operate with the Drainage Operating Department.

Some of the men from Central Power Station cleared the feeder to Station No. 3, and at 12:30 noon, two large pumps were started at that station. Current had to be taken off of this line, however, at 3:12 p. m. in order to enable the linemen to clear the lines going to Stations No. 6 and 7 of the tangle of wires of the electric light, telephone and telegraph companies at Frenchmen Street and the Louisville & Nashville Railroad crossing. At 7:20 o'clock p. m. this was accomplished, and lines to Stations 6 and 3 were cleared and two large pumps started at each of those stations.

On Friday, October 1st, at 8:40 a. m., the pumps were also started at Station No. 7. Line troubles still made it impossible to operate at all from Power House No. 2, or to operate any of the pumps at Stations 1, 2 or 5, and since the water had accumulated in the low areas which Stations 1 and 2 could not relieve until Stations 6 and 7 had removed the greater portion of the water thus accumulated, there was nothing to be gained by the operation of Stations 1 and 2. Station 5 could have helped Station 3, but was of relatively little importance, being only of small capacity.

Levees below Maximum Lake Level

On Thursday morning the lake level still maintained its Maximum elevation, and there were numerous points along the various navigation and drainage outfall canals and on
p7the rear protection levees where lake water was entering the city in large amount. The overflow from these sources, added to the average of about 7¼ inches of rainfall, was a most discouraging feature of this day's development, and added materially to the delay in getting all parts of the city free of water.

We have subsequently run lines of levels over all of the protection levees, some 45 miles of lines having been covered, and in view of a lake elevation of 26.2 C. D. for a considerable period, it is felt that this feature should receive serious consideration.

Levees should be Raised

The tidal elevation of 26.2 C. D. is several inches above any previous record, and our levels indicate that stretches of protection levees on the lake front, or along the navigation or drainage outfall canals, aggregating some seven miles, are slightly below this elevation with very considerable lengths of depressions which are very materially below said elevation. In view of this new high tide record and the condition, as above stated, the recommendation of the Chief Engineer of the Orleans Levee Board looking toward more substantial and higher levees for the protection of the city against lake tides is heartily endorsed. The Sewerage and Water Board is constructing its own outfall pumping stations with a view of being able to maintain them in operation with a maximum water elevation of 30 C. D. on their discharge side.

Crevasses Closed

The point which threatened the most seriously was the protection levee along the line of Florida Avenue. On Friday morning it was discovered that the tide water from the swamps was running over great lengths of the New Orleans Terminal Company's tracks, and breaks were starting in several places. The Chief Engineer of the Orleans Levee
p8Board and the officers of the New Orleans Terminal Company were at once notified of this condition. The Terminal Company, I understand, have their right-of‑way conditioned upon the maintenance of an adequate levee at this point. An examination on Friday p. m. showed that no steps were being taken to stop the crevasses, which, by this time, were of sufficient proportion to really endanger this area, supplying more water than the pumps were removing, and a letter from the general manager of the Terminal Company, received by your President Friday afternoon, indicated that he did not consider that anything could be done until the swamp water in the rear went down. We then insisted upon immediate action and, in order to get it, furnished the labor, much material in the way of sacks and lumber, and supervision, and the Terminal Company furnished trains and other material, and on Saturday morning the work of closing these crevasses was started and by Saturday night it was completed, with the result that a most disastrous flooding of the lower section of the city was averted.

It is the intention to bill the Terminal Company for the actual cost of labor and material furnished in this instance.

By Friday night the area between the two navigation canals was practically free of water, and by Saturday night most of the water had been removed from the large low area above the New Basin Navigation Canal, and back of Clara Street.

The portion of the city below Elysian Fields Avenue and back of St. Claude Avenue, however, which is very sparsely settled, was not relieved of water until Wednesday, October 6th, despite the fact that the pumps at Station 3 operated continuously from the afternoon of the day following the storm. This being due to the crevasses above mentioned, and to other overflows of levee lines protecting this area.

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Damage Sustained by Sewerage and Water Board

At all of the Sewerage and Water Board stations and at the Washington Avenue yard, more or less damages have been sustained, mostly to the roofs of the buildings; slates, tiles, etc., having been blown off. No material damage has been suffered by the machinery, although some of the motors were wet and had to be thoroughly dried out before they could be safely operated.

Temporary repairs to the roofs were made and permanent repairs will be made as soon as the necessary material can be procured.

The greatest damage is in the breaking off of the upper portion of both stacks at the Central Power Station, and the destruction of the stack at Station No. 5 and the Central Power Station, where one stack fell through same. At the Central power Station, with oil fuel, much shorter stacks will answer equally well, and there will, therefor,º be no necessity to renew the long stacks which were required in the original construction when coal was used as fuel. At Station 5 a somewhat shorter stack can be substituted, with temporary repair of roof, since the old station will probably go out of commission as soon as the new station now under construction is completed.

At Central Power Station the roof of one of the great fuel oil tanks was torn off and carried •300 feet and fell upon the pipe line leading from another of these tanks, breaking same outside of the masonry wall provided to impound the oil in said tanks in case of a break in the tank, thus allowing the escape of some 2,000 barrels of fuel oil.

Underground Cables Probably No More Certain of Operation

Following this storm, a general and careful overhaling of the transmission lines will be necessary. The greater
p10part of the troubles on these lines were due to the fact that telegraph, telephone and electric light and other wire lines crossed over same and fell upon them, causing short-circuits, or that trees fell across them tearing them down. The line from Central Power Station to Station 5, however, is in very soft ground and was blown over in many places, and a few poles on other lines, subjected to unusual stresses and so located that satisfactory guy wires could not be used, or where other special conditions existed, were also badly bent over. We have often had the suggestion that underground cables would avoid line troubles of the character occasioned by this storm. To some extent they would, but the cost of an underground system is absolutely prohibitive, and underground systems, we know from experience, are also subject to troubles of other kinds, and in case of trouble in an underground system following a great storm, where the ground through which it passes is under water, the difficulty of quick location of the trouble and of its prompt repair is even greater than with an overhead system. Pumping stations, each operated by steam, or other power at each station, is another solution which various critics of the existing system occasionally advise. Not being responsible in any way for the original adoption of the general system now in use, I can say, without hesitation, that I know of no other system that could have been adopted which would have given a better service during the hurricane or remained in service longer or gotten back into service more promptly than the system here in use, and especially of none which can be more economically or satisfactorily operated.

Operation of Sewer and Water Systems

During the late afternoon of the storm of September 29th, as an example of underground lines and the troubles which a hurricane may cause to them, it may be noted that falling walls in several cases caused the breaking of water mains, or of large connections, or of fire hydrants in various widely scattered parts of the city, and the water consumption rate
p11was more than doubled, resulting in a slight reduction of pressure in New Orleans, and for a short time a considerable reduction in Algiers. Until these various breaks were all located and closed, the filters and pumps were called upon to furnish an excessive amount of water, which they did; and the clear water reservoir also was drawn upon very heavily Wednesday night and on Thursday. The output from the filters, however, was maintained fully up to the usual standard, though the forces at both the pumping station and at the water purification station were pushed to the utmost to maintain the supply and pressure.

It is fortunate that the largest break, which was caused by a falling church steeple, happened to be in an 8‑inch line, instead of in a 12 or 20‑inch line, and in an area which was not flooded after the storm, so that it was located and closed early Thursday morning. A break in a larger main, or in a main in a locality where prompt discovery and closure would have been far more difficult, could easily have occurred and might have given very serious trouble.

In Algiers, the lowering of the pressure for a short time, due to a sudden break, caused the water to lower greatly in the stand pipe during the heavy blow, thus exposing it to wind action without its full weight of water to resist same, and bringing unusual stresses upon its cast iron foundation braces, several of which were cracked. These braces can be renewed of steel at comparatively small expense, and no considerable cost or damage will result.

The main sewerage pumping station, the Algiers Station, and Station B at Jourdan Avenue, were operated continuously during and after the storm, and the various sub-stations, which were by‑passed immediately after the storm, were put back into operation as soon as the flooding due to the storm water had been lowered in the various areas which they serve. The sewers, of course, were filled to the limit of their capacity with storm water, which entered as seepage water at the cement joints of the sewers themselves and of the house connection lines and into manholes in the higher
p12portions of the city, and in the lower areas the water ran from the manhole tops into the nearest drains, when the water in the drains was first lowered. Additional pumps at the various sewer pumping stations, which pumps are now under contract, will largely eliminate such overflow from sewer manholes after the full equipment of drainage pumps, also under contract, is installed, since these latter will tend to the more prompt removal of storm waters through the drains themselves, and to the maintaining of water levels and conditions in the drainage system which will not throw so much drainage work upon the sewers, and will in turn permit of their more prompt relief.

Co‑operation of Board's Departments and Forces

From what has been said, it will be noted that by Saturday night, following the storm of 7¼ inches and the tidal overflow of levees in the rear of the city of very considerable extent, nearly all of the flooding, even of the lowest areas, had been removed and first aid applied to roofs, transmission lines, etc. This was only accomplished by the most arduous efforts not only of the Drainage Operating forces, under the direction of Mr. Alfred Raymond, but also by the co‑operation of the Sewerage and Water Operating forces, the Drainage Maintenance and Construction forces, under Mr. Alfred F. Theard, and the Sewerage and Water Maintenance and Construction forces, under Mr. John T. Eastwood. Telephones were not available almost anywhere. The Ford cars had to, and did, take their place, and had to go through storm and water to carry messages, to obtain men or to get material. The Washington Avenue Yard was all but inaccessible, due to fallen wires, and to the high water in the Claiborne Canal. One team of mules belonging to the Board was killed by a live wire at the bridge at Washington Avenue and Claiborne Street, and others escaped by narrow margins. Both during and after the storm, day or night, the Board's men, from the highest to the lowest, accepted
p13any task that was assigned to them, regardless of whether it was in their particular department, and put their best efforts into its prompt execution. And the spirit of helpful co‑operation and mutual appreciation which was shown throughout was most admirable.

Rainfall During and Subsequent to Hurricane

On Sunday morning, October 3rd, just when things were approaching normal, another rain commenced, giving over 5 inches more of rain by Monday noon, October 4th, but with no period of unusual intensity. This time all the stations all along the line were operated in a very nearly normal manner, and but little flooding in low areas resulted. When, however, this was followed again on the 12th by a rainfall of 7.2 inches, of which nearly 5 inches fell between 12:30 and 4 p. m., and the rainfall came upon a city with its soil thoroughly saturated, and its streets still littered with debris of the hurricane in the form of leaves, branches, slates from roofs, etc., in sufficient intensity to wash everything to the catch basins and obstruct the drainage openings, there was, of necessity, a very considerable amount of temporary local flooding in the higher portions of the city, and some repetition of the flooding in the lower area, due to the very great volume of water to be removed, which is beyond the present capacity of Stations 6 and 7 until they receive their added pumping capacity, now under contract.

During this unusual severe storm, Station 1, with its new pumps, made a splendid showing, and could have made a much better showing had Station 6 also been able to carry away as much water as Station 1 could have discharged.

Algiers Drainage Conditions

In the Algiers outfall canal the effect of the succession of storms of the last 15 days, with their total of, approximately, 20 inches of rainfall, is very clearly shown. On
p14September 29th, before the hurricane, the canal stood at elevation 18.5 C. D. By night, with 7¼ inches of rainfall, its elevation had risen to 23.0 C. D. I am advised that the three pumps of the Jefferson-Plaquemines Drainage District worked almost continuously, and that there was no considerable overflow of tide water into this district. By Monday, October 4th, the water in the Algiers Outfall Canal had fallen to 21.8 C. D., or 1.2 feet, then followed over 5 inches of rain, which raised the level to 23.2 C. D. or 1.4 foot, on October 5th. By October 12th this level was again reduced to 21.8 C. D. and the storm of the 12th and 13th again raised the water, this time to elevation 23.6 C. D., or 1.8 feet. At this level of 23.6 C. D. there is a very narrow margin to permit of the by‑passing of the discharge of the major portion of the Algiers storm flows, which is essential to the proper drainage of Algiers, and it is necessary to throw upon the pumps at that station a larger proportion of the storm runoff than they can take care of as promptly as might be desired, since the built‑up portion of Algiers is reaching back to land which is only at elevation 24 C. D., or 4/10 of a foot higher than this outfall canal level.

I am advised that additional pumps are very soon to be installed at the Jefferson-Plaquemines Drainage Station and that the boilers for their operation are already erected.

With present pumping capacity at the Jefferson-Plaquemines station operated to its limit it would require over 9 days to pump out as much water as a 7‑inch rain will precipitate over the area tributary to it. Under ordinary conditions, the total pumpage does not have to nearly approximate the total rainfall, because of absorption by the soil and evaporation, but when one great rain follows two others in rapid succession, evaporation and absorption become very small factors and all drainage systems are put to the hardest possible test.

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Rainfall Records in Comparison with Recent Heavy Rainfalls

Fortunately such great rainfalls as seven inches in twenty-four hours occur but seldom.

The rainfall records of the Sewerage and Water Board and of its predecessor, the Drainage Commission, go back to 1894, inclusive, with six recording gages located in various portions of the city. The year 1915 will complete the 22 years of these records.

Prior to the storm of September 29th, there were only two storms which recorded as much as seven inches in twenty-four hours on any of these gages.

Maximum Rainfall in Fifteen Days 22.24 Inches

During the period from September 29th to October 13th, 1915, inclusive, there were two storms, each of which recorded over seven inches of rainfall in twenty-four hours, and one storm between these two which exceeded the maximum storms of many of the years of this period.

In 1903 the maximum rainfall recorded was 9.21 inches in 15½ hours, and in 1907 8.12 inches in 26 hours.

The maximum recorded on

September 29th, 1915, was

8.36 inches in

21 hours

October 12th and 13th, 1915, was

7.96 inches in

21¾ hours

October 3rd, 4th, 5th and 6th, 1915, was

5.92 inches in

60 hours

Making a total for the 15‑day period of

22.24 inches

The average record of all six gages for this period was 19.24 inches, and the record of the United States Weather Bureau's office at New Orleans was 19.91 inches for the same period.

The Sewerage and Water Board records from average gages for the 22‑year period show that the heaviest rainfall
p16for any three calendar months was in March, April and May of 1912, with 30.81 inches; for any two calendar months was in April and May, 1907, with 26.62 inches; for any one calendar month was in September, 1898, with 16.10 inches; for any previous consecutive period of 15 days was in April and May, 1907, with 14.1 inches, as against 19.24 inches average by the Board's gages, and 19.91 inches by the United States Weather Bureau for September 29th to October 13th, inclusive, 1915.

Capacity of City Drainage System

If the above described rainfall had been spread uniformly over this period of fifteen days, it would have amounted to 1⅓ inches per day, and would have given the City Drainage System no trouble at all, because the present capacity of pumps discharging into the various high level outfall canals is sufficient, under storm conditions, to discharge into said canals each day as much water as a 3½‑inch rainfall precipitates upon the •25,000 acres of existing drained area of the city, and when the additional pumps now under contract are installed this discharging capacity will be equal to all of the precipitation which a 7⅓‑inch rainfall in 24 hours pours upon the city.

Rural Drainage Projects Most Affected

The aggregate of rainfall, however, is a serious matter in connection with rural drainage projects, and it is with a view of showing that these have encountered very much the worst conditions for a 15‑day period which have been recorded in the last 22 days that the above is written.

Infrequency of Rainfall of Seven Inches and Over.

From Sewerage and Water Board records prior to September 29th, it would have been fair to assume that a rainfall
p17of 7 inches, or over, in 24 hours would happen on an average about once in eleven years, and that the average year would show a maximum rainfall in 24 hours of about 4½ inches, with a wind velocity never exceeding 70 miles and a lake tide elevation not above 25.7 C. D.

Improbability of Repetition of Recent Rainfall Phenomena

The fact that a single 15‑day period has given two rainfalls of over 7 inches, and a third of over 4½ inches, with a lake tide elevation of 26.2 C. D., and a sustained wind velocity of over 80 miles an hour, with gusts of much greater intensity, only renders the more remote the probability of a repetition of any of these things in the early future, and with the lessons which they have brought in mind, there is no reason why this city and its surrounding country should not continue, even more successfully than heretofore, the developments in all directions which have been so well advanced and which for the most part have been but little injured.

Board's Forces Assisting City Departments

Upon several occasions since the hurricane a number of Sewerage and Water Board teams and drivers have been delegated to assist the Division of Public Works as much as possible in the removal of trash from the streets of the city; and the Division of Public Works has been doing all that it can to rid the city streets in every way possible of the debris which the hurricane has left behind it. It will necessarily be some time, however, before this task can be completed, and in the meantime the effect of trash obstructing catch basins will be felt, not only in retarding the run‑off of the surface water through the drains, but also in causing a largely increased proportion of water from the higher areas of the city to enter the sewers as seepage water, thus increasing the time and extent of overcharged sewers.

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In Conclusion

In view of the very great severity of the hurricane of the 29th ultimo, and of the unprecedented succession of subsequent rainfalls and their intensity, it is safe to say that no city anywhere in the world could have withstood these conditions with less damage and less inconvenience than has New Orleans, and the feeling on the part of those in the most responsible positions in the Sewerage and Water Board service is entirely one of gratitude and satisfaction that the city as a whole and the Board's service have all escaped with only a little inconvenience and a relatively insignificant amount of minor damage, which soon can be fully restored.

Respectfully,
Geo. G. Earl,
General Superintendent.

Thayer's Notes:

a
I transcribed the text from the original 18‑page pamphlet, printed by American Ptg. Co., 535‑7 Poydras (New Orleans), with no date of publication. My transcription has been carefully proofread and is thus presumably errorfree; if, of course, you should find the inevitable error, please let me know.

b
In modern terminology, this was a Category 1 hurricane: sustained winds of 74‑95 miles per hour.

c
C. D. = above Cairo Datum. Cairo, Illinois, a town on the Mississippi River at the southern tip of the state of Illinois, served as a reference point for water levels until well into the 20c. Cairo Datum is no longer used; Old Cairo Datum (1871‑1910) was 21.26 above Mean Sea Level 1929, and New Cairo Datum (1910‑1929) was 20.434 above Mean Sea Level 1929. The latter can be taken as a good approximation of sea level at the Louisiana coast, although it is no longer used either. For further comprehensive details, see
Surveying Little Egypt, A height modernization of the Memphis district by the U.S. Army Corps of Engineers, by Milton Denny.

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